DSR-920 4DTV receiver lithium battery issue

Discussion in 'Free To Air (FTA) Discussion' started by JeremielMontanez, Jul 19, 2012.

  1. JeremielMontanez

    JeremielMontanez Thread Starter Member

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    I just got a General Instrument model DSR-920 4DTV receiver. It hasn't been used in years, but looks to be in very good condition. I've been reading the forum threads about this receiver and I understand there is an issue with the lithium battery failing and ruining the receiver. So I opened up the receiver and checked the battery voltage. It is still reading 6.3 volts which I believe means the unit is still good at present. But I don't want to take any chances. There is no telling how long before the battery fails. The receiver has been in storage for 5 years and still has the original battery. I just ordered a new battery today from Digi-Key, their number 439-1008-ND which is a Tadiran Batteries - TL-5955/P. I will be changing the battery as soon as the new one gets here. Wish me luck, and if anyone who has done this before wants to give me some encouragement, and pointers it would be very much appreciated.
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  2. Bongu

    Bongu Addicted beyond recovery Pub Member / Supporter

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    The battery replacement MUST MUST MUST MUST MUST be done with power to the unit. Before you replace the battery, make sure the UID on the back of the receiver matches the UID on the diagnostics screen. If no match, the receiver is only good as a mover and possibly some ZK channels. Do a GOOGLE search for battery replacement instructions if you want to try it yourself. A company called ATS is recommended if you are unsure of your ability to do this. The DCII chip must not lose power while doing the replacement.

    Sent from my Timex Sinclair using SatelliteGuys
  3. JeremielMontanez

    JeremielMontanez Thread Starter Member

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    Thanks for the reply! It took me a while to locate the instructions for pulling up the the diagnostics screen. I don't have a manual. I finaly found instructions an looked. There is both an IUD number and a unit number present. The unit number matches the unit number on the back of the receiver. So I guess I'm good to go once the battery I ordered gets here. There are good instructions on how to do the battery change several places on line. I'm going to go ahead and do it. Thanks again for the response. From what I've been reading I think if I succeed the work will just be starting as it looks like I will have to bring the programing up to date.
  4. wallyhts

    wallyhts SatelliteGuys Family Staff Member

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    Go for it. The 920 is not that bad. However I have never replaced a battery on a 920 live "power plugged in".

    I always take the 4d board out and install the new battery after that I remove the old battery.
  5. JeremielMontanez

    JeremielMontanez Thread Starter Member

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    Yes! That is what I will do to. I think the concern is that if the battery is real weak and you unplug the receiver you will loose the UID. But this receiver has been unplugged and in storage for five years the man who gave it to me told me. Before I had done much research and before I had ever plugged it in I opened up the receiver and measured the battery voltage, it was at 3.6 volts. It must have been a real good battery because the man owned and used this receiver for many years before he put it in storage. I did eventually plug the receiver in when I was informed that I needed to check if the UID and receiver number were still in memory. I had a feeling they were but I plugged it in and checked anyhow after finally locating instructions on how to do so. I think this battery is still charged enough to last another day or two until the new battery gets here. I will solder in the new one with the old one still in place, then remove the old one. Meanwhile I'm going crazy reading about how to reprogram this receiver to bring it up to date. I think that after I install the battery I, going to set this aside for awhile. I still have to dig up the 12 foot dish this Sunday, bring it home and install it here. No wonder all this stuff was free. No one else is crazy enough to get involved doing all this work, but I'm loving it. :O)
  6. Bongu

    Bongu Addicted beyond recovery Pub Member / Supporter

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    The 920 sounds like it is similar to the digitrans units if you can easily remove the board to work on it. I have a 922 and it is not so simple to remove the board...

    I'm glad wallyhts popped in and cleared it up. I am one of the few that did the battery swap with a powered receiver. My trusty butane soldering iron is the best for "hot" work if you excuse the pun.

    C band work is a great educational experience. It involves geometry, basic engineering principles, and hard labor while digging. Pretty well rounded if you ask me.


    Sent from my Timex Sinclair using SatelliteGuys
  7. Lone Gunman

    Lone Gunman Active SatelliteGuys Member

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    I replaced mine in my 920 about 3 or 4 years ago and it was a piece of cake. I also did the DCII module at the same time but wouldn't now as they are no good for anything any more. I connected that new battery at both ends of the original battery then cut the old one out. Used a zip tie to fasten it to the board and it was done. Oh, and all this was done with the power plug DISCONNECTED! One of the set of instructions I have stated that the capacitors would hold enough charge to keep the ID in tact for a short time without battery power so I didn't worry about horking it up.

    But of course, your mileage may vary!;)
  8. sergei

    sergei Active SatelliteGuys Member

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    I've replaced the battery in all 4 of my 920's and I didn't have to remove the board. The 920 is real easy to work on, just make sure that you have the new battery installed before removing the old one. I also put some Mylar under the board to keep from shorting out the battery lead
  9. JeremielMontanez

    JeremielMontanez Thread Starter Member

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    Thanks for the information on the DCII module. I was thinking about replacing that one too while I was at it. Now I won't bother. Just out of curiosity what was it used for originally? I'm new to Satellite TV though I've been in armature radio since ten years old or so. I'm 70 now years young. :eek:)
  10. JeremielMontanez

    JeremielMontanez Thread Starter Member

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    You are right! If I insulate under the board with Mylar or some such material it would be would be good insurance. I'm not going to remove the board all the way either. It will be much easier that way. I appreciate all the tips you guys have given me. I can't wait for the battery to get here. This will be easy... I hope. :O)
  11. JeremielMontanez

    JeremielMontanez Thread Starter Member

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    I just looked it up. DigiCipher 2, what the heck it's just like me. We are not totally obsolete yet :O). It will only take me another couple of minutes to change that battery too, and then it will be there if I ever need it.
  12. JeremielMontanez

    JeremielMontanez Thread Starter Member

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    I received my lithium battery from Digi-Key today and successfully installed it. The new battery is dated 5/12. The old battery is marked 97-6 which I think means June 1997. That makes it 15 years old. It is still reading 3.66 volts. I don't understand why it was necessary to change it, but better safe than sorry. In place the new one is reading 3.57 volts. I hope it turns out to be as good a battery as the old one was. The UID is still reading the same number, and the receiver number is still the same as the number on the back. Until I plugged this receiver in the other day it had not been plugged in since January 2000 when the person I got it from unplugged it and put it in storage because he had to move to an apartment where he could not put up a dish antenna. It has never had a master reset done which means it still has the original maps in it. Do any of you know which of the satellites the designators such as G9 and the others used by 4DTV correspond to. (which satellite each represents). I'm still working on getting my 12 foot dish cleaned up and installed. It's coming along nicely though. Once everything is set up You will be seeing me on the Map Masters forum.
    Last edited: Jul 25, 2012
  13. wallyhts

    wallyhts SatelliteGuys Family Staff Member

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    I think G9 is 123.

    T4 ( 89W)
    G7 (91W)
    T5 (97W)
    W1 (103W)
    G9 (123W)
    C3 (131W)
    G1 (133W)
  14. doug900

    doug900 Member

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    My DSR922 has a 3v battery in it, not 3.6v, and it looks factory. Does the 920 take a 3.6v, and the 922 take a 3v? I measured it and I'm getting 3.3v (definitely a good sign). I just purchased the receiver and wanted to make sure the battery was up to snuff. Anybody know if the 2 models use different voltages?
  15. trinidex

    trinidex Active SatelliteGuys Member

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    I have both and they both have 3.6v batts
  16. doug900

    doug900 Member

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    Strange. Unless someone had replaced it with the wrongvoltage battery, could there have been a modification from Motorola to use 3.6vinstead of 3v, and I would have the early one, or the late one if they decidedthat 3v worked. I guess my concern is, what is the critical voltage cutoffbefore ram is cleared ( basically that's what it is. Just like a computer, ifyou lose power, you lose all data in ram). What numbskull designed thisbeautiful system? Wouldn't non-volatile memory make more sense, so that taking thebattery out would not affect the memory contents?
  17. Bongu

    Bongu Addicted beyond recovery Pub Member / Supporter

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    NV memory is much more susceptible to intrusion attempts and tampering. They(M) knew what they were doing when they designed it with the battery. They just didn't expect the units to be used for so long.

    Sent from my Timex Sinclair using SatelliteGuys
  18. Anony55

    Anony55 Active SatelliteGuys Member

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    Doug,

    I don't think it makes much difference between 3.0 & 3.6 volts. I've opened several DCII models including home & commercial units, and have found both types. Finding a 3.6v battery in a particular model doesn't guarantee that the next unit of the same model will also be 3.6... it could be either.

    This is just a guess on my part, but I've often wondered if the big M didn't go to 3.0v batteries with smaller mAh numbers in hopes that the units wouldn't last as long. I highly doubt that a 3.0v 300 mAh battery would last as long as a 1200 mAh 3.6v battery. Of course, there are other factors that go into how long a battery will last. But I expect that the big M knew what they were doing when they changed.

    For that matter, I suspect the usage of a coin battery in some units may have been to discourage battery replacement all together.

    As always, I could be wrong. ;)

    Cheers

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